SEER is like miles per gallon on a car.
We want to get a unit that operates efficiently for the climate it is in.
Example - Michigan only runs ac 3 months heavy...it doesnt warrant spending extra on a high efficient unit.
Texas - Here it pays to buy a high seer unit because it runs so much.
16 seer and higher (higher the seer the better) is great for TX.
But also in TX it is important not to oversize as the humidity needs to be removed with longer run times.
Any ac contractor can run a load calc for you. It takes location, sq ft, windows, insulation
etc....and gives a recommended size. Sight unseen I would say you will be in the area of 3 to 3.5 ton. based on sq ft.
Thr brand is secondary to a good install...Trane, Bryant, Carrier
, American Standard, Lennox....are all good makes. The key is getting a contractor you feel comfortable with.....AND....does a load calc.